Effects of krill oil containing n-3 polyunsaturated fatty acids in phospholipid form on human brain function: a randomized controlled trial in healthy elderly volunteers

Chizuru Konagai,^1,2 Kenichi Yanagimoto,³ Kohsuke Hayamizu,³ Li Han,³ Tomoko Tsuji,³ Yoshihiko Koga<sup>2

1</sup>Department of Food and Nutrition, Japan Women's University, Bunkyo-ku, Tokyo, Japan; ²Department of Neuropsychiatry, Kyorin University School of Medicine, Mitaka, Tokyo, Japan; ³Human Life Science R&D Center, Nippon Suisan Kaisha Ltd, Chiyoda-ku, Tokyo, Japan

Background: Krill oil, rich in n-3 (omega-3) polyunsaturated fatty acids (PUFAs) incorporated in phosphatidylcholine, has been reported to have many effects on physiological function. However, there are few studies using psychophysiological methods published that describe the effects of krill oil on brain function. We investigated the influence of ingestion of krill oil on cognitive function in elderly subjects by using near-infrared spectroscopy and electroencephalography.
Methods: A randomized, double-blind, parallel-group comparative study design was adopted. Forty-five healthy elderly males aged 61–72 years were assigned to receive 12 weeks of treatment with: medium-chain triglycerides as placebo; krill oil, which is rich in n-3 PUFAs incorporated in phosphatidylcholine; or sardine oil, which is abundant in n-3 PUFAs incorporated in triglycerides. Changes in oxyhemoglobin concentrations in the cerebral cortex during memory and calculation tasks were measured. The P300 component of event-related potentials was also measured during a working memory task.
Results: During the working memory task, changes in oxyhemoglobin concentrations in the krill oil and sardine oil groups were significantly greater than those in the medium-chain triglyceride group at week 12. The differential value for P300 latency in the krill oil group was significantly lower than that in the medium-chain triglyceride group at week 12. With regard to the calculation task, changes in oxyhemoglobin concentrations in the krill oil group were significantly greater than those in the medium-chain triglyceride group at week 12.
Conclusion: This study provides evidence that n-3 PUFAs activate cognitive function in the elderly. This is especially the case with krill oil, in which the majority of n-3 PUFAs are incorporated into phosphatidylcholine, causing it to be more effective than sardine oil, in which n-3 PUFAs are present as triglycerides.

Keywords: eicosapentaenoic acid, docosahexaenoic acid, phosphatidylcholine, event-related potential, near-infrared spectroscopy, dorsolateral prefrontal cortex